rust/src/libstd/uv_hl.rs

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#[doc = "
High-level bindings to work with the libuv library.
This module is geared towards library developers who want to
provide a high-level, abstracted interface to some set of
libuv functionality.
"];
export high_level_loop, high_level_msg;
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export run_high_level_loop, interact, exit;
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import libc::c_void;
import ptr::addr_of;
import comm::{port, chan, methods};
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import ll = uv_ll;
#[doc = "
Used to abstract-away direct interaction with a libuv loop.
"]
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enum high_level_loop = {
async_handle: *ll::uv_async_t,
op_chan: chan<high_level_msg>
};
#[doc="
Represents the range of interactions with a `high_level_loop`
"]
enum high_level_msg {
interaction (fn~(*libc::c_void)),
#[doc="
For use in libraries that roll their own `high_level_loop` (like
`std::uv::global_loop`)
Is used to signal to the loop that it should close the internally-held
async handle and do a sanity check to make sure that all other handles are
closed, causing a failure otherwise. This should not be sent/used from
'normal' user code.
"]
teardown_loop
}
#[doc = "
Useful for anyone who wants to roll their own `high_level_loop`.
# Arguments
* loop_ptr - a pointer to a currently unused libuv loop. Its `data` field
will be overwritten before the loop begins
* msg_po - an active port that receives `high_level_msg`s. You can distribute
a paired channel to users, along with the `async_handle` returned in the
following callback (combine them to make a `hl::simpler_task_loop` varient
of `hl::high_level_loop`)
* before_run - a unique closure that is invoked before `uv_run()` is called
on the provided `loop_ptr`. An `async_handle` is passed in which will be
live for the duration of the loop. You can distribute this to users so that
they can interact with the loop safely.
* before_msg_process - a unique closure that is invoked at least once when
the loop is woken up, and once more for every message that is drained from
the loop's msg port
* before_tear_down - called just before the loop invokes `uv_close()` on the
provided `async_handle`. `uv_run` should return shortly after
"]
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unsafe fn run_high_level_loop(loop_ptr: *c_void,
msg_po: port<high_level_msg>,
before_run: fn~(*ll::uv_async_t),
before_msg_process:
fn~(*ll::uv_async_t, bool) -> bool,
before_tear_down: fn~(*ll::uv_async_t)) {
// set up the special async handle we'll use to allow multi-task
// communication with this loop
let async = ll::async_t();
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let async_handle = addr_of(async);
// associate the async handle with the loop
ll::async_init(loop_ptr, async_handle, high_level_wake_up_cb);
// initialize our loop data and store it in the loop
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let data: hl_loop_data = {
async_handle: async_handle,
mut active: true,
before_msg_process: before_msg_process,
before_tear_down: before_tear_down,
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msg_po_ptr: addr_of(msg_po)
};
ll::set_data_for_uv_handle(async_handle, addr_of(data));
// call before_run
before_run(async_handle);
log(debug, "about to run high level loop");
// enter the loop... this blocks until the loop is done..
ll::run(loop_ptr);
log(debug, "high-level loop ended");
}
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#[doc = "
Provide a callback to be processed by `a_loop`
The primary way to do operations again a running `high_level_loop` that
doesn't involve creating a uv handle via `safe_handle`
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# Warning
This function is the only safe way to interact with _any_ `high_level_loop`.
Using functions in the `uv::ll` module outside of the `cb` passed into
this function is _very dangerous_.
# Arguments
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* hl_loop - a `uv::hl::high_level_loop` that you want to do operations against
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* cb - a function callback to be processed on the running loop's
thread. The only parameter passed in is an opaque pointer representing the
running `uv_loop_t*`. In the context of this callback, it is safe to use
this pointer to do various uv_* API calls contained within the `uv::ll`
module. It is not safe to send the `loop_ptr` param to this callback out
via ports/chans.
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"]
unsafe fn interact(hl_loop: high_level_loop,
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-cb: fn~(*c_void)) {
send_high_level_msg(hl_loop, interaction(cb));
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}
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fn exit(hl_loop: high_level_loop) unsafe {
send_high_level_msg(hl_loop, teardown_loop);
}
// INTERNAL API
// data that lives for the lifetime of the high-evel oo
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type hl_loop_data = {
async_handle: *ll::uv_async_t,
mut active: bool,
before_msg_process: fn~(*ll::uv_async_t, bool) -> bool,
before_tear_down: fn~(*ll::uv_async_t),
msg_po_ptr: *port<high_level_msg>
};
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unsafe fn send_high_level_msg(hl_loop: high_level_loop,
-msg: high_level_msg) {
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comm::send(hl_loop.op_chan, msg);
ll::async_send(hl_loop.async_handle);
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}
// this will be invoked by a call to uv::hl::interact() with
// the high_level_loop corresponding to this async_handle. We
// simply check if the loop is active and, if so, invoke the
// user-supplied on_wake callback that is stored in the loop's
// data member
crust fn high_level_wake_up_cb(async_handle: *ll::uv_async_t,
status: int) unsafe {
log(debug, #fmt("high_level_wake_up_cb crust.. handle: %? status: %?",
async_handle, status));
let loop_ptr = ll::get_loop_for_uv_handle(async_handle);
let data = ll::get_data_for_uv_handle(async_handle) as *hl_loop_data;
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// FIXME: What is this checking?
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if (*data).active {
let msg_po = *((*data).msg_po_ptr);
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while msg_po.peek() {
let msg = msg_po.recv();
if (*data).active {
alt msg {
interaction(cb) {
(*data).before_msg_process(async_handle,
(*data).active);
cb(loop_ptr);
}
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teardown_loop {
begin_teardown(data);
}
}
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} else {
// FIXME: drop msg ?
}
}
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} else {
// loop not active
}
}
crust fn tear_down_close_cb(handle: *ll::uv_async_t) unsafe {
let loop_ptr = ll::get_loop_for_uv_handle(handle);
let loop_refs = ll::loop_refcount(loop_ptr);
log(debug, #fmt("tear_down_close_cb called, closing handle at %? refs %?",
handle, loop_refs));
assert loop_refs == 1i32;
}
fn begin_teardown(data: *hl_loop_data) unsafe {
log(debug, "high_level_tear_down() called, close async_handle");
// call user-suppled before_tear_down cb
let async_handle = (*data).async_handle;
(*data).before_tear_down(async_handle);
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ll::close(async_handle as *c_void, tear_down_close_cb);
}
#[cfg(test)]
mod test {
crust fn async_close_cb(handle: *ll::uv_async_t) unsafe {
log(debug, #fmt("async_close_cb handle %?", handle));
let exit_ch = (*(ll::get_data_for_uv_handle(handle)
as *ah_data)).exit_ch;
comm::send(exit_ch, ());
}
crust fn async_handle_cb(handle: *ll::uv_async_t, status: libc::c_int)
unsafe {
log(debug, #fmt("async_handle_cb handle %? status %?",handle,status));
ll::close(handle, async_close_cb);
}
type ah_data = {
hl_loop: high_level_loop,
exit_ch: comm::chan<()>
};
fn impl_uv_hl_async(hl_loop: high_level_loop) unsafe {
let async_handle = ll::async_t();
let ah_ptr = ptr::addr_of(async_handle);
let exit_po = comm::port::<()>();
let exit_ch = comm::chan(exit_po);
let ah_data = {
hl_loop: hl_loop,
exit_ch: exit_ch
};
let ah_data_ptr = ptr::addr_of(ah_data);
interact(hl_loop) {|loop_ptr|
ll::async_init(loop_ptr, ah_ptr, async_handle_cb);
ll::set_data_for_uv_handle(ah_ptr, ah_data_ptr as *libc::c_void);
ll::async_send(ah_ptr);
};
comm::recv(exit_po);
}
// this fn documents the bear minimum neccesary to roll your own
// high_level_loop
unsafe fn spawn_test_loop(exit_ch: comm::chan<()>) -> high_level_loop {
let hl_loop_port = comm::port::<high_level_loop>();
let hl_loop_ch = comm::chan(hl_loop_port);
task::spawn_sched(task::manual_threads(1u)) {||
let loop_ptr = ll::loop_new();
let msg_po = comm::port::<high_level_msg>();
let msg_ch = comm::chan(msg_po);
run_high_level_loop(
loop_ptr,
msg_po,
// before_run
{|async_handle|
log(debug,#fmt("hltest before_run: async_handle %?",
async_handle));
// do an async_send with it
ll::async_send(async_handle);
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comm::send(hl_loop_ch, high_level_loop({
async_handle: async_handle,
op_chan: msg_ch
}));
},
// before_msg_drain
{|async_handle, status|
log(debug,#fmt("hltest before_msg_drain: handle %? %?",
async_handle, status));
true
},
// before_tear_down
{|async_handle|
log(debug,#fmt("hl test_loop b4_tear_down: async %?",
async_handle));
});
ll::loop_delete(loop_ptr);
comm::send(exit_ch, ());
};
ret comm::recv(hl_loop_port);
}
crust fn lifetime_handle_close(handle: *libc::c_void) unsafe {
log(debug, #fmt("lifetime_handle_close ptr %?", handle));
}
crust fn lifetime_async_callback(handle: *libc::c_void,
status: libc::c_int) {
log(debug, #fmt("lifetime_handle_close ptr %? status %?",
handle, status));
}
#[test]
fn test_uv_hl_async() unsafe {
let exit_po = comm::port::<()>();
let exit_ch = comm::chan(exit_po);
let hl_loop = spawn_test_loop(exit_ch);
// using this handle to manage the lifetime of the high_level_loop,
// as it will exit the first time one of the impl_uv_hl_async() is
// cleaned up with no one ref'd handles on the loop (Which can happen
// under race-condition type situations.. this ensures that the loop
// lives until, at least, all of the impl_uv_hl_async() runs have been
// called, at least.
let work_exit_po = comm::port::<()>();
let work_exit_ch = comm::chan(work_exit_po);
iter::repeat(7u) {||
task::spawn_sched(task::manual_threads(1u), {||
impl_uv_hl_async(hl_loop);
comm::send(work_exit_ch, ());
});
};
iter::repeat(7u) {||
comm::recv(work_exit_po);
};
log(debug, "sending teardown_loop msg..");
// the teardown msg usually comes, in the case of the global loop,
// as a result of receiving a msg on the weaken_task port. but,
// anyone rolling their own high_level_loop can decide when to
// send the msg. it's assert and barf, though, if all of your
// handles aren't uv_close'd first
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comm::send(hl_loop.op_chan, teardown_loop);
ll::async_send(hl_loop.async_handle);
comm::recv(exit_po);
log(debug, "after recv on exit_po.. exiting..");
}
}